The 5-aminosalicylate drugs have a well established role in the management of adults with ulcerative colitis. Study of these drugs in the pediatric population has been very limited. Asacol, a ph sensitive polymer coated oral preparation of 5-aminosalicylate, will be studied to determine the optimal dose to treat ulcerative colitis in children without associated diversity. Approximately 25 pediatric patients weighing at least 27KG will enrolled into the maintenance phase on this study. The patient will be blindly randomized to receive either the equivalent of 50mg/kg/day or 15mg/kg/day for one year. Patients will followed for one year or until clinical relapse of disease activity. The hypothesis of this study is based on the probability that 30% of patients receiving the higher dose of Asacol will relapse compared with 55% rate of relapse in patients receiving the lower dose of Asacol.